On Thu 2019-03-14 15:06:16, Rasmus Villemoes wrote:
> Currently, setting device_name to a 15-character name requires
> avoiding a trailing newline (e.g. by using 'echo -n' or 'printf'),
> which is inconsistent and potentially surprising. Instead of
> potentially including a newline in the copy and then overwriting it,
> move the newline detection logic to the sysfs handler itself, and
> handle it by passing a smaller buffer size to
> netdev_trig_set_device().
>
> This also makes netdev_trig_set_device() a better fit for a future
> user, which will not need the newline truncation logic.
>
> We still have to tell userspace we consumed all the bytes it gave us,
> so we have to stash the original value of size.
>
> Signed-off-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Acked-by: Pavel Machek <pavel@xxxxxx>
> ---
> drivers/leds/trigger/ledtrig-netdev.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/leds/trigger/ledtrig-netdev.c b/drivers/leds/trigger/ledtrig-netdev.c
> index 21605033e322..c35439291424 100644
> --- a/drivers/leds/trigger/ledtrig-netdev.c
> +++ b/drivers/leds/trigger/ledtrig-netdev.c
> @@ -114,8 +114,6 @@ static void netdev_trig_set_device(struct led_netdev_data *trigger_data,
>
> memcpy(trigger_data->device_name, buf, size);
> trigger_data->device_name[size] = 0;
> - if (size > 0 && trigger_data->device_name[size - 1] == '\n')
> - trigger_data->device_name[size - 1] = 0;
>
> if (trigger_data->device_name[0] != 0)
> trigger_data->net_dev =
> @@ -134,7 +132,11 @@ static ssize_t device_name_store(struct device *dev,
> size_t size)
> {
> struct led_netdev_data *trigger_data = led_trigger_get_drvdata(dev);
> + size_t orig_size = size;
>
> + /* Ignore trailing newline */
> + if (size > 0 && buf[size - 1] == '\n')
> + size--;
> if (size >= IFNAMSIZ)
> return -EINVAL;
>
> @@ -147,7 +149,7 @@ static ssize_t device_name_store(struct device *dev,
> set_baseline_state(trigger_data);
> spin_unlock_bh(&trigger_data->lock);
>
> - return size;
> + return orig_size;
> }
>
> static DEVICE_ATTR_RW(device_name);
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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